As information communication technology advances, various data formats are changed from an analog format to a digital format in which processing is easy, and quality is not degraded even after several-time reproduction and copy. With the advancement of the Internet, digital data is widely distributed.
In such digital data, digital video is widely used on the Internet due to the advancement of compression technology such as joint photographic coding experts group (JPEG).
The digital video is easy to copy and distribute, and thus, when the digital video is indiscriminately distributed without an author's consent in an open space such as the Internet, it is unable to protect the intellectual property rights of an author and a copyright owner.
To overcome such limitations, a watermarking technique that determines the falsification and unlawful use of digital video and enables the claim of copyright is proposed as a technique that adds an imperceptive signal into digital video and uses the imperceptive signal for authentication and protection of copyright.
Various watermarking techniques have been developed at present, but a technique using a pseudo random sequence is mainly used at present. Also, instead of a spatial domain, a transformed domain using a discrete Fourier transform or a discrete cosine transform is mainly used for a domain into which watermark is inserted.
However, the related art method inserts watermark without systematically sorting the kinds of contents in an operation that stores contents and performs content conversion, and thus, a user needs to again sort contents by kind. For this reason, much time is unnecessarily expended, and work efficiency is low, causing inconvenience in use.